CLINICAL AND HEALTH SERVICES RESEARCH CORE Abstract The Clinical and Health Services Research (CHSR) Core promotes multidisciplinary intervention research in diverse clinical settings that mitigates the impact of mental health disorders, substance use, and other HIV comorbidities and advances the uptake and efficacy of pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) approaches. The CHSR Core will foster linkages and research collaborations that integrate clinical and social/behavioral approaches, and contribute expertise in HIV comorbidities research in clinical settings. Over the next five years, the Core will promote and support high quality research in areas in which psychological factors, mental health and treatment for substance use disorders within health systems are of utmost importance. Areas of special emphasis will include: engaging youth who are either HIV-infected or at risk for HIV, including transgender youth; and optimizing health care for those with substance use disorders and/or mental health comorbidities, and for women experiencing interpersonal violence and/or involved in the correctional system. As part of CIRA's New England HIV Implementation Science Network, the CHSR Core will emphasize development and support of research on linkage, retention and other implementation gaps in the treatment cascade, and issues particularly salient to HIV care in small clinics and health systems. The CHSR Core will also lead CIRA's international research development efforts, promoting and supporting strategic international collaborations with potential to have a high impact on the epidemic occurring in high prevalence areas. Through joint meetings with the Community Research and Implementation Core, CHSR will promote and support research addressing gaps across the continuum of care that entail both community-based and health care system approaches. Dr. David Fiellin, Professor of Medicine and Public Health, will serve as CHSR Core Director. Dr. Fiellin has conducted extensive research on substance use and mental health and has expertise in IS. Dini Harsono, MSc will serve as the Core Assistant Director. Other senior investigators in the Core have substantial research experience related to the interface between primary care, HIV, addiction and mental health comorbidities, and bring both research and clinical backgrounds in nursing, pediatrics, addiction medicine, geriatrics, and psychiatry and expertise with diverse populations such as veterans, people who use drugs and alcohol, youth, elderly, gay/bisexual men and others. These include: Dr. Brian Forsyth, Professor of Pediatrics who will lead the CHSR Core's international research program and facilitate a new Youth Work Group; Dr. Paul Cleary, Professor of Public Health and Director of CIRA, an expert in health services research; Dr. Frederick Altice, Professor of Medicine, who conducts implementation research focused on diverse risk groups both domestically and internationally; Dr. Gerald Friedland, Professor of Medicine, recognized internationally for his extensive research relating to HIV care and its comorbidities; Dr. Ann Kurth, Dean of the School of Nursing who provides leadership in international research on the continuum of care; and others.